(i) Field of the Invention
The present invention relates to radiation sensitive polymer materials, particularly positive type radiation sensitive polymer materials having high radiation sensitivity.
(ii) Description of the Prior Art
In recent years, there is a tendency to require integrated circuits (IC) having higher density and higher integration. In the manufacture of IC, the formation of fine resist patterns having line width of less than 1 .mu.m is thus required.
Radiation sensitive resists sensitive to radiations such as electron beams, X-rays and ion beams are suitable for the formation of fine resist patterns.
There are two types of radiation sensitive resists, namely negative type and positive type.
Radiation sensitive resists of negative type can, considering their reaction mechanism, inherently withstand influences caused by dry etching which is conducted at the time of fine pattern formation, and are good in sensitivity but poor in resolution.
On the other hand, radiation sensitive resists of positive type are inherently better in resolution than the negative type, considering the reaction mechanism. However, these positive type resists are attacked at their end portions in dry etching operation, and poorer in sensitivity than the negative type resists.